rimfire question

tlo7mm · Posted: Thu Nov 20, 2014 5:08 am Post subject: rimfire question

Has anyone attempted to use the software for rimfire cartridges? I understand this is primarily for hand loaders but i was only curious if anyone had used it to collect data on the factory ammo you purchase for your rimfires.

Vince · Posted: Thu Nov 20, 2014 5:58 pm Post subject: Re: rimfire question

Can't say I have mate, but ranges are so short with the venerable rimfire, it is hardly worth the trouble of looking for trajectory data. Also, trying to get a BC for the little lead projectile would be extremely difficult.

My experience shows me that with modern high velocity .22 rimfire rounds, when zeroed at 50yards, they are five and one half inches low at 100 yards. You could use them for hunting beyond that range, but it would be very hard work.

Where PB would come in handy would be in recording your shots on the target so that you have a record of individual brands of ammo.

DallanC · Site Admin Joined: Jan 18, 2005 Posts: 3572 Location: Utah

I don't personally for the reasons Vince stated. But knowing muzzle and X yard velocities it is easy to compute the BC of a bullet and from there, chart the trajectory with the muzzle velocity.

It might be worth it for my 17HMR which 100 yard shots are quite fun and easy.

-DallanC

Elvis · Posted: Fri Nov 21, 2014 12:04 am Post subject: Re: rimfire question

Radar will be able to help..flick him a PM as he is shooting .22 out to 3-400yards.

tlo7mm · Posted: Fri Nov 21, 2014 3:05 am Post subject: Re: rimfire question

I was able to obtain some of the BC for factory ammo that I shoot, it was rather easy however there is a lot of factory ammo that I do shoot through my rimfires that I cannot seem to find the BC for. It really wasn't something I figured was often done I am just curious about the data. I will definitely hit Radar up because I am interested in learning a bit about long range shooting with .22. Thanks Dallan, Vince and Elvis.
Dallan, my mom has an old Remington Model 512 .22 that I have done some long range shooting with reasonable success but I do agree that the .17 hmr is probably better suited for this. I would be interested to chrony my .17 because it is a rather unique gun from what I can tell. I have never seen another although I know that someone out there must have one. It is a Taurus pump action.

Vince · Posted: Fri Nov 21, 2014 7:03 am Post subject: Re: rimfire question

I never thought of the .17 rimfire. When I hear "rimfire" I automatically think .22 . My shooting buddy has a CZ .17 rimfire and that thing is so accurate it is scary. He shoots extremely tight groups at 100m, I'm talking less than 5mm, so it would be interesting to see how it performs at longer ranges which I'm sure it will do very well.

Elvis · Posted: Fri Nov 21, 2014 8:38 pm Post subject: Re: rimfire question

tlo7mm wrote:

. I would be interested to chrony my .17 because it is a rather unique gun from what I can tell. I have never seen another although I know that someone out there must have one. It is a Taurus pump action.

I thought they were in .45 long colt!!!!

tlo7mm · Posted: Fri Nov 21, 2014 11:21 pm Post subject: Re: rimfire question

They made the. 17 modeled after the old winchester 22 pump but when Taurus bought rossi they stopped making all of their Rifles except the. 45 lc until recently. They are now making AR type Rifles.

MacD · Posted: Sat Nov 22, 2014 7:28 am Post subject: Re: rimfire question

Don't forget the. 22 WMR? I bought boxes of every 22lr and 22WMR I could find when I got my convertable revolver. I didn't shoot over a chronograph but recorded such things as groups, mis-fires and jams. I still have samples of each round and it would be interesting to shoot 5 of each over the chrony to get speed and deviation. From my tests it was readily apparent quality control for the 22lr varied widely from one maker to the next.

PaulS · Posted: Sun Nov 30, 2014 11:18 am Post subject: Re: rimfire question

I have used several ballistics software and spreadsheets to predict the trajectory of 22 LR ammunition. I have chronographed several hundred rounds and with all this I can tell you that the velocity on the box is nothing more than an estimate and any round that states velocity at or above 1200 fps will not match any ballistic profile. I have a list of 22 bullets and their ballistic coefficients and they range from .130 to .085.
My testing was done at 20, 25, 40, 50, 60, 75 and 80 yards.
The reason that "standard", "high" and "hyper-velocity" 22 LR ammo won't match any ballistic softare is that between 40 and 60 yards it goes through the transonic velocity region and that completely destabilizes the flight of the bullet. At transonic speeds (about 80 -110% of the speed of sound) the 22 begins to "cone" in flight - spiraling out of the line of flight before once again settling down on an entirely new trajectory path.

The subsonic ammo is much better in maintaining a pure trajectory and will fit a G1 ballistic prediction almost perfectly as long as the temperature is high enough to keep the ammo below the speed of sound (local speed of sound). The denser the air the lower the speed of sound so those of us who live above sea level, with humidity that is moderate to high have the ability to shoot faster 22s without going through the transonic range but even with the lowest density air if your ammo starts out at 1200 fps you are going to find a specific range, beyond which the ammo just doesn't group. You will also note the "change in trajectory" caused by the coning of the bullet when it aproaches the speed of sound.

The problem is worse for bullets with center of gravities towards the heal of the bullet because in the transonic period the center of pressure moves forward on the bullet. The center of gravity wants to move ahead of the pressure, "flip around backwards", but it is spinning so, much like a top that is winding down it begins to wobble and that wobble is in a circular movement that takes the bullet off its course. When it drops through the speed of sound the bullet will restabilize on some course that is unpredictable. (at least by any software I have seen or used)